Signal



v p 1930. c. A. CAMPBELL SIGNAL Filed D80. 28, 1929 2 Sheets-Sheet l Sept. 30, 1930. cAMPBELL 1,776,966

S IGNAL Filed Dec; 28. 1929 2 Sheets-Sheet 2 nil v M acm w Patented Sept. 30, 1930 UNITEDSTATES PATE T OFFICE- oHARLEsA. OAMPRELL,,O wATERrowN, NEW YORK, ASSIGNOR '170 THE NEW YORK AIR BRAKE COMPANY, A CORPORATION OE NEW JERSEY I SIGNAL 1 I Application filed December '28, 1929. Serial No.-417,142.

This invention relatesto signals "and particularly to signal discharge valves for. pneumatic train pipe signal systems extensively used on railway trains. j

In such systems there is a signal train pipe which extends the length of the train. Such train pipe is wholly distinct from the brake pipe and is maintained charged with air under a chosen pressure, say pounds per square inch, by a pressure reducin'gfeed valve deriving air from the main reservoir on the locomotive, and controlled by a choke or restriction which limitstherate of supplyto the signal train pipe. There is a diaphragm actuated signal valve on the locomotive, the valve controlling flow of air to the whistle to blow thelatter. The diaphragm is subject to train pipe pressure, and so arranged that it opens the valve momentarily and blows the whistle if the train pipe pressure is reduced. Such reductions of train pipe pressureare producedby opening anyone of 'a plurality of discharge valves connected with'the' train pipe, there being usually at least one such valve on each car. The rate of discharge produced by such discharge valves must e'x-- c eed the feed rate of the feed valve. V

In the signal code from one to seven suc-' cessive blastsare required, and inrlong trains.

undue depletion of pressure in the train pipe." Faulty manipulation is virtually impossible.

towardwhich present practice tends, signal failures after two or three-blasts are common. The present invention isbased on the dis covery that these failures are caused by faulty manipulation, and by the uncontrollable characteristics of the simple vent valves heretofore used as dischargelvalves, which result in excessive venting at'each open'ing' ofa discharge valve.

Theimproved discharge valve measures the air discharged at each manipulation, the quantity vented being so chosen as to avold interference by the feed valv whichstarts to feed afterthe first reduction, and to avoid In a seriesof tests on a twenty car train conventionally equipped, the discharge valve on the twentieth carfbeing used, the prior art discharge valve failed afterseven blasts With the most favorable manipulation, failed after one blast in one instance, and averaged 3% blasts in a series ofsixv graduated tests. The valve here described and claimed, applied to the same signal train pipe, produced twenty four"successive blasts in the poorest test, sixty-three, in the best, and averaged 45% in a series of six tests which accurately paralleled the series of six made with the prior art Valve. 'Moreover, the present device does not require the precise manipulation heretofore essential.

-The preferred embodiment of the invention is illustrated in the accompanying drawing, in which, I r

'F'g. l is a diagram of the system as a whole for" engine tender and three cars;

Fig, 2 is a fragmentary view showing the valve and its connections with thetrain pipe and measuring chamber.

Fig. 3 is an axial section through the discharge valve; i i A r Fig. dis an elevation partly in section on the line 3-3 of Fig. 2. v

1 Referring first to Fig. 1, 5represents any suitable source of compressed air, conveniently the main reservoirfon the locomotive. 6 is a cut-out cock, 7 astrainer, and 8 a pressure reducing feed valve. The feed valve Sdischarges through a flow-limiting choke Thesignal train pipe has the usual hose connections .lZbetween cars, with cut-out cocks 13. The signalwalve 14: on the locomotiveis connected withabranch of the signal pipe 11 and controls flow to the signal whistle 15. All the'above parts are of any usual construction. Each car carries at least one of the improved signal discharge valves involving the novel features of the present invention,'the preferred embodiment of which will now be described" (see particularly Figs. 3

aud t) Qn each car there is a branch pipe 16 leading from signal train pipe 11 to a discharge. valve generally indicated by the numeral 17 applied to its body. A pipe 18 connects the valve with'a measuring chamber 19 (sec Fig. 2). The chamber 19 may be of any suitable size, but an effective volume of 92 cubic inches has been used with success.

The body 17 is divided into three distinct chambers 21, 22 and 23 by two valve seats 24 and 25 which control ports respectively between chambers 21 and 22 and between chambers 22 and 23. Chamber 21 is vented to atmosphere at 26. Chamber 22 is connected at 27 with branch pipe 18 which leads to the measuring chamber 19, and chamber 23 is connected by union 28 with train pipe branch 16.

Seating upward against seat 25 is the main valve 29 having an extension 30 guided in threaded plug or closure 31. The valve 29 has a sealing insert 32. The valve is urged closed by a spring 32 and its pilot 34 is counterbored to receive the lower end of stem 3:") which fits loosely therein. Chamber 21 is open at its upper end and serves as a guide for a combined plunger and spring-seat 8G pinned at 37 to the upper end of stem and protruding from bot y 17. An actuating lever 38, of the known, double fulcrum type, has hooks 39, engaging the removable fulcrum pins 41, 41, and an eye 42 for the attaclnn eut of the usual conductors signal cord.

The lever 38 engages the member 36 between the hooks 39, and if the lever is swung in either direction from the position shown in Fig. 3, it will depress the member 86 and stem against the resistance of spring 43.

The upper end of stem 35 is reduced in diameter, as shown, to produce a shoulder 44. Slidable on and closely fitting this reduced portion, and limited in its downward motion relatively to stem by shoulder 44 is a valve 45. Valve 45 is urged toward shoulder 44 by spring 46 which reacts between the valve and member 36.

The body 17 is supported fixedly by screws or bolts passing through the lugs 47.

The parts are preferably so proportioned that in normal position (see Fig. 3) valve 45 is held unseated by shoulder 44 and the end of stem 35 is out of contact with valve 29 and spaced far enough from the same to ensure closure of valve 45 against seat 24 before valve 29 is opened by stem Any equivalent arrangement which would ensure closure of valve 45 not later than the initial opening of valve 29 might be used, The simultaneous opening of both valves even for a brief interval would detract from the accuracy of the measuring function and'is to be avoided.

To actuate the signal, the lever 38 is swun in either direction from the position of Fig. 3, closing valve 45 and opening valve 29. Pres sure equalization occurs between signal pipe 11 and chamber 19. Thus av measured quantity of air is discharged from the signal pipe 11, initiating a pressure wave which travels along the signal pipe to the signal valve diaphragm which responds and blows one blast of the whistle. hen released lever 38 is returned to the position of Fig. 2 by spring 43 causing closing of valve 29 and opening of valve 45 in the order stated, this isolating chamber 19 from the signal pipe 11 and then venting the chamber to atmosphere. The parts are then ready for another manipulation.

As the valves offer short flow paths of large capacity, the air flow is almost instantaneous and precise timed manipulation of the valve is not necessary. If the lever 38 be moved its full stroke a failure to function and blow the whistle under twenty-four successive blasts will not occur, even from the last car of a twenty car train. As such signals are used only on passenger trains, the operation of the device materially exceeds the requirements of service.

The device is illustrated in a form preferred because actual trials demonstrate a high standard of performance, and because susceptible of economical manufacture, but it may be modified in ways which will suggest themselves to those skilled in the art, and still embody the inventive concept.

lVhat is claimed is,

1. In a signal system, the combination of a source of air under pressure; a signal train pipe; a feed valve delivering air from said source to said pipe and operative at all times to feed air upon a reduction of train pipe pressure and thus tend to maintain a substantially constant pressure in said pipe; means limiting the flow rate through said feed valve; a signal mechanism responsive to pressure reductions in said train pipe; and at least one discharge valve mechanism including a volume measuring chamber adapted when actuated to discharge a measured volume of air from said signal train pipe.

2. In a signal system, the combination of a. source of air under pressure; a signal train pipe; a feed valve delivering air from said source to said pipe and operative at all times to feed air upon a reduction of train pipe pressure and thus tend to maintain a substantially constant pressure in said pipe; means limiting the flow rate through said. feed valve; a signal mechanism responsive to pressure reductions in said train pipe; and at least one discharge valve mechanism comprising a measuring chamber, two valves, one controlling a vent from said chamber, and the other a passage from the signal pipe to said chamber, and means for opening said valves in alternation with one another.

3. In a signal system, the combination of a, source of. air under pressure; a signal train pipe; a feed valve delivering airfrom said source to said pipe and operative at alltimes to feed air upon a reduction of train pipe pressure and thus tend to maintain a substantially constant pressure in said pipe; means lin iting the flow rate through said feed valve; a-signal mechanism responsive to pressure reductions in said train pipe; and at least one discharge valve mechanism comprising a measuring chamber, two poppet valves one controlling a vent from the chamber and the other controlling a. connec-- tion betwen the train pipe and chamber, and

an actuator having a lost motion connection with both poppet valves, arranged first to seat either valve and then open the other.

4. In a signal system, the combination of a source of air under pressure; a signal train pipe; a feed valve delivering air from said source to said pipe and operative at all times to feed airupon a reduction oiftrain pipe pressureandthus tend to maintain a substantially constant pressure in said pipe;

ing means urglng said actuator in a direction to unseat the first named poppet valve and manual means for shifting said actuator in the reverse direction. 7

5. A signal discharge valve comprising in combination, a measuring-chamber; avalve body having a train pipe connection, a connection to said chamber, and a vent; two re versely seated poppet valves in said body, one controlling flow from said chamber to said vent and opening in the direction of venting flow, the other controlling fiow' from the train pipe connection to said chamber andclosing in the direction of flow to the chamber; spring means urging said valves closed; and an actuator movablein reverse directions to unseat said valves selectively.

6. A signal discharge. valve comprising in combination a measuring chamber; a valve. body having a train pipe connection, a connection to said chamber, and a vent; two reversely seated poppet valves in said body, the first controlling flow from said chamber to said vent and opening inthe direction of venting flow, the second controlling flow from the train pipe connection to said cham' her and closing in the direction of flow to the chamber; an actuator slidable through the first valve and arranged to engage and unseat said'valvesselectively when shifted in reverse directions; a spring urging said actuator in adirection to unseat the first valve; a spring reacting'between'the actuator and first valveand arranged toseat said first'valve whenthe actuator is shifted to unseat the second valve; and yielding means urging the second valve closed. r

In testimony whereof I have signed my name to this specification.

, CHARLES A. CAMPBELL. 

